GOP presidential front-runner Mitt Romney commands double-digit leads in South Carolina and Florida, but Newt Gingrich’s troubled campaign is showing signs of resurgence in the Palmetto State just three days before its pivotal primary, according to a TIME/CNN/ORC poll released Wednesday.

The poll, which surveyed likely Republican voters between Friday and Tuesday, found Romney claiming 33% support in South Carolina, down four points from two weeks ago. Gingrich notches 23%, a gain of five points that marks a reversal of the steep slide he suffered in December. Rick Santorum slipped three points into third place at 16%, while the standing of Ron Paul (13%) and Rick Perry (6%) remained virtually unchanged.

Gingrich’s standing-O debate performance on Monday night in Myrtle Beach, hailed by national and state activists as a pitch-perfect defense of conservatism, may have moved the needle even further. A flash poll taken Tuesday night by Rasmussen found Gingrich pulling within three points of Romney.

The former Speaker performs well among men, 28% of whom support him in the TIME/CNN/ORC poll (vs. 32% for Romney) and those without college degrees, while Romney’s strongest support lies among those with degrees and non-Evangelicals, of whom he claims a robust 47%. Born-again Christians continue to splinter between Gingrich (23%), Santorum (20%) and Perry (9%), and as a result, Romney claims 26% plurality support among that group. Romney also wins 26% of Tea Party backers, but 31% of them now break for Gingrich, a notable rise since early January, while 20% go to Santorum.

The advertising war has been fierce in South Carolina, and though Romney and his allies are outspending all comers, the poll results suggest the first dedicated anti-Romney air attacks of the campaign–as well as Gingrich’s relentless drumbeat on the trail– are taking their toll. Even so, there is little time left for Gingrich to close the gap, and voter opinions in South Carolina are beginning to harden. A majority, 57%, now say they will definitely support their preferred candidate in Saturday’s primary.

In Florida, where 53% of likely voters say they’re already locked into their vote for Jan. 31, Romney is running away with the race. Forty-three percent of likely voters now back the former Massachusetts governor there, an 18-point leap since early December. That makes for more than a 20-point lead on his closest rival, Santorum, who also shot up 18 points over the same time period, but started from near-zero support. Gingrich clocks in at third with 18%, a stunning 30-point drop since early December. Santorum’s rise has been fueled by the backing of born-again Christians, 34% of whom now say they’ll vote for the former Senator, but Romney dominates in every other demographic group, including conservatives and Tea Partyers.

Methodology: The poll surveyed 1,508 adults, including 472 registered Republicans, by telephone between Jan. 13 and 17 in Florida, and identified 391 likely voters. In South Carolina, a total of 1,525 adults were interviewed over the same time period and 505 likely voters were identified. All respondents were asked about their registration status and basic demographics, and the sample was weighted to reflect statewide Census figures for gender, race, age, education and region of the state. The results carry a sampling error of +/-5 percentage points in Florida and +/-4.5 points in South Carolina.